Process for producing pure guarseed flour

ABSTRACT

The object of the present invention is a process for producing pure guarseed flour which produces a transparent and highly viscous solution when dissolved in water. Despite extensive purification, the process provides good yields of pure guarseed flour. The process comprises acid treatment of the initial material, washing the acid-treated split with water and/or neutralization with an aqueous alkaline solution, washing with water and dewatering using an aqueous alcohol solution. Transparent, highly viscous solutions of pure guarseed flour obtained by this process are primarily used in the food industry.

BACKGROUND OF THE INVENTION

The object of the present invention is a process for producing guarseedflour which, when it is dissolved in water, produces a transparentsolution of high viscosity, where the process produces good yields ofthe pure flour despite extensive cleaning. Transparent, high-viscositysolutions of pure guarseed flour are of great importance primarily inthe food industry.

Guarseed flour is used as a thickening agent in the textile andexplosives sectors, as a binding agent in the paper industry, as aflocculant in ore extraction and as an auxiliary material in theextraction of natural gas and oil, in the pharmaceutical and cosmeticfields, and as a thickener, emulsifier and (co-)stabilizer in the areasof foods and food technology.

In pharmaceutics guarseed flour is used for example for spray embeddingof vitamins, in order to increase their shelf stability. In addition,the use of guarseed flour in sprays guarantees nearly monomoleculardistribution of the active ingredients and consequently improved,uniform resorption, which is desirable in the case of asthma medicationsand various allergy remedies. Because of the extremely low proteincontent of the pure guarseed flour there is no danger of the developmentof an allergic reaction to a medication which contains this substance.Additional applications in this field are the formulation ofdelayed-action tablets and as a means of lowering the cholesterol level.In the field of medicine guarseed flour is also used as an emulsifierand stabilizer in contrast agents.

Among other applications, guarseed flour has also proven to be an idealdietetic substance, since its building blocks, the so-calledgalactomannans, are not attacked by human stomach and intestinalenzymes. This is to be expected, since in the human digestive system upto the large intestine there are neither β-mannanases norα-glacto-sidases present, which would be necessary to break down thesebuilding blocks. Since the building blocks of guarseed flour do notenter into the human metabolism, there is no reason to regard guarseedflour as a carrier or supplier of calories. Since guarseed flour isconstituted of completely neutral polysaccharides, or more precisely ofgalactomannans, which have neither uronic acid nor other ionogenicgroups, they represent a completely harmless material in physiologicalterms.

An additional advantage in terms of its use as an ingredient in foods isits complete neutrality of taste. It is used in reduced-calorie orreduced-fat foods or drinks which are often perceived as “thin” by theconsumer. Adding guarseed flour to these products lends them a“creamier” consistency. In the production of fruit juices guarseed flouris used in order to re-suspend the fruit pulp uniformly, in puddings andcremes it functions as a thickener, in ice creams, milkshakes, moussesand similar products it works as a stabilizer. With traditional guarseedflour preparations, only mild molecular interaction with the biopolymerxanthane was found. While mixing these two colloids did produce asynergistic increase in viscosity, a specific formation of gel as in thecase of carubin, carob seed flour and xanthane, did not occur. If a 1:1mixture of the guarseed flour in accordance with the invention andxanthane is heated together and allowed to cool at 4° C. (refrigeratortemperature), a gel forms. An advantage of this combination of guarseedflour and xanthane lies in the fact that the gel from these twocomponents melts at body temperature, so that it is superbly suited forthe production of gelatin-like foods, as a vehicle for the delivery ofmedications in pill form, and the like. Furthermore, guarseed flour andxanthane are used in combination as co-stabilizers in the production ofsalad dressings, since this combination, in contrast to guarseed flourused alone, is resistant to acids.

Guarseed flour is obtained from the endosperm of the guar bean(cyamopsis tetragonobolus). Guarseed flour consists in large measure ofgalactomannans, i.e. of polysaccharides whose fundamental chain islinked in the 1→4 direction by β-glycoside bonds and is made up ofmannose which is joined to galactose via primary OH groups. The ratio ofunsubstituted mannose to mannose substituted with galactose is about2:1, with the substituted units not alternating strictly but arranged inthe polygalactommannan molecules in groups of two or three. Theguar-galactomannans form highly viscous solutions in water even inslight concentrations. Acueous solutions of 1 percent by weight ofcommon commercial guarseed flour produce viscosities of around 3000 to6000 mPa·s.

Guar-galactomannans are divided into cold water soluble, hot watersoluble and insoluble galactomannans on the basis of chemical andphysiochemical differences.

To obtain and purify the guarseed flour the guarseed is treatedmechanically; this produces approximately 35 parts unrefined guarendosperm halves and approximately 60 parts guar germ flour. The guargerm flour consists primarily of the germ of the seed, the scraped offbean skin, and small pieces of the endosperm. The endosperm completelyencloses the germ and is in turn surrounded by the seed skin. Aprotein-rich, aleuron-like cell layer encloses the endosperm, whosecells are closely interlocked with the endosperm. This protein-richlayer adjoins the seed skin.

The unrefined endosperm halves can be further cleaned mechanically andproduce splits of varying quality in terms of their protein content,their components which cannot by hydrolyzed by acid (A.I.R.) and theamount of skin present. The term “split,” which is usual among thespecialists, is synonymous with the term “endosperm halves.”

Although guarseed flour is already in wide use as a thickening agent,there is a desire to improve its purity and, related thereto, itsphysical and physiological properties. For its use in foods, inparticular, the purity of the guarseed flour is of great importance.Also desirable is more complete utilization of the main components ofthe endosperm, so that the latter can be used to a greater degree in thecorresponding branches of industry in place of cellulose derivatives orother polysaccharides which are clearly soluble in water, or syntheticpolymers which are clearly soluble in water.

If the products consisting of pure guarseed flour which are currentlyavailable on the market, when processed into flour, are dissolved inwater at 25° C. or at 86 to 89° C. for 10 minutes, they produce cloudysolutions. If the insoluble material in these solutions is centrifugedout at high centrifugal forces (>35,000×g), it turns out that 23-35% ofthe guarseed flour comprises material which is centrifuged out.Microscopic investigations have shown that the centrifuged precipitateis made up primarily of skin fragments, protein materials, insolubleperipheral cells, intact unopened cells of the inner endosperm and otherimpurities of the seeds or splits. Chemical derivatization of theguarseed flour (etherification, hydroxypropylation, cationization, etc.)makes it possible to produce products with significantly improveddissolving behavior in water, and along with that, greater transparencyof the solutions.

One of the processes used heretofore for obtaining pure guarseed flouruses chlorinated solvents, such as trichlorethylene (see EP 0 130 946,Meyhall Chemical AG). The solution was fractionated by simply being leftto stand or by centrifuging, which led to the formation of aprotein-rich fraction (floating fraction) and the separation of aprotein-poor fraction (precipitating fraction).

It has been possible to show that the highest floating fraction ofendosperm processed into flour, such as guar CSA 200/50, can contain upto 25% proteins, and the precipitating fraction, which makes up 75% ofthe pure flour, contains about 1.5 to 1.6% protein. The precipitatingfraction is used for example to produce cationic derivatives, which canbe dissolved to produce clear aqueous solutions. A disadvantage of thisprocess is that finely-ground skin fragments are also found in theprecipitating fraction. An additional disadvantage is the use ofhalogenated solvents, since a specific weight of 1.47 to 1.48 kg/l isrequired. Proteins have a density of 1.3 kg/l and the galactomannans adensity of 1.5 to 1.55 kg/l depending upon their moisture content. Theguarseed flour produced by the process described here is suitedprimarily for technical applications. In food preparation this guarseedflour is probably not usable, since remnants of the halogenated solventwhich was used remain in the end product; 10 ppb are found in fractionsextracted with ethanol. Halogenated solvents are toxic and caustic tovarying degrees, and frequently possess allergizing properties. Thisprocess should be avoided for environmental reasons as well.

An additional process for producing pure guarseed flour was proposed asearly as 1969. It comprised an alkali treatment of pre-swollen splits atelevated temperatures, in which 100 parts of alkali were absorbed by 100parts of SPS. The large quantity of alkali, i.e. NaOH, had to be washedout. This was carried out with cold water at a proportion of 1:80(SPS:H₂O) and in a water extraction step with isopropanol (IPA), inwhich at the same time the residual NaOH in the purified splits wasneutralized with acetic acid.

After grinding, a pure guarseed flour of high quality was obtained in ayield rate of 60-70%, based on the raw material SPS (simply purifiedsplits). In 1969 this process was improved by Stein, Hall & Co., LongIsland City, N.Y. The present washing process with water is based onthat process. The purpose of this process for purifying guar derivativesis to remove skin fragments and peripheral cell layers, and also toremove byproducts of the various etherification reactions(hydroxypropylation, carboxymethylation and cationization and/orcombinations of these).

Despite the intensive purification processes described above, it has notyet been possible to obtain in an economical way pure, non-derivatizedguarseed flour which produces a clear aqueous solution with highviscosity whale at the same time delivering good yields.

The disadvantages of the processes used to date for purifying andobtaining pure guarseed flour are:

1. large losses of valuable portions of the endosperm during themechanical cleaning, and resultant small yields of pure guarseed flourin proportion to the source material;

2. skin fragments which continue to be found on the splits of varyingquality, and which interfere with the functioning of the modified endproducts to a large extent;

3. peripheral, protein-rich cells of the aleuron layer which hardlyswell in water and which likewise have a negative influence on thefunctioning of the end product;

4. presence of other impurities from the guarseeds, such as woodyparticles, which should not be present.

It was desired, therefore, to develop a process for producing pureguarseed flour which would eliminate the aforementioned disadvantagesand deliver good yields of pure guarseed flour which, after dispersionin water, would produce a clear, highly viscous solution, to be usedprimarily for example in the food industry, the pharmaceutical and paintindustries, and in the extraction of oil.

SUMMARY OF THE INVENTION

The objective of the present invention is to fulfill the aforementionedrequirements, i.e. to obtain good yields of pure guarseed flour througha new production process, especially guarseed flour suitable for thefood industry, which produces clear aqueous solutions of high viscosity.

The process according to the invention for producing pure guarseed flouris defined in patent claim 1, and comprises the following stages:

(a) treatment of guar splits with acid;

(b) one-time or repeated washing of the acid-treated splits with waterand/or neutralization with an aqueous alkaline solution;

(c) treatment of the splits with an aqueous alkaline solution;

(d) washing the splits with water;

(e) extraction of the water from the splits with an acueous alcoholsolution.

DETAILED DESCRIPTION OF THE INVENTION

A first prerequisite for obtaining pure guarseed flour is to improve thestarting material, the so-called splits. The splits, covered with skins,should constitute up to 42.5% of the seed by weight. The overlappingskin-endosperm portions, which amount to 13.5 percent of the seed byweight, are essentially insoluble in water. The embryo of the seed makesup the remaining 44%. These quantity indications show that thetheoretical yield of splits usable for the invention, without skin andwithout overlapping parts, is 32%.

The pure guarseed flour according to the invention can be produced mostadvantageously from splits which have a protein content of 4.2% and anA.I.R. proportion of 1.8%.

Pure guarseed flour, whose source material according to the inventionpreferably consists of splits of the highest purity available at thetime, can be produced after acid treatment using 70% to 96%, preferably96%, sulfuric acid (8% to 12% based on the weight of the split) at roomtemperature or elevated temperatures. If the concentration of thesulfuric acid is lower than 70% by weight, then smaller yields of pureguar products are produced, and in addition with lower viscosities.

The order of the various steps of treatment after the acid treatment canbe varied, which causes the resulting guarseed flour to acquirediffering properties in terms of its viscosity, translucency, proteinand A.I.R. content. For example, the order of the handling steps can bechosen from the following technical sequences, to name just a fewpossibilities:

1. washing—alkaline treatment—washing—water extraction andneutralization as needed, preferably with an organic acid—drying and/orgrinding

2. neutralization of the acid-treated splits—washing—alkalinetreatment—washing—water extraction and neutralization as needed,preferably with an organic acid—drying and/or grinding

Dehydration with isopropyl alcohol or some other alcohol such asmethanol, ethanol, N-propyl alcohol, N-butyl alcohol or equivalent is anabsolute “must,” if good products are to be produced. Treatment with IPAimproves the clarity of the aqueous guarseed flour solutions. Ifappropriate, at the same time as the IPA treatment a neutralization with99% acetic acid or some other so-called food acid such as citric acid,tartaric acid, formic acid or equivalent can be performed.

The level of moisture during the grinding significantly influences theproperties of the mealy end product. The higher the moisture content ina technically practicable dimension, the larger is the quantity of thesoluble polysaccharides, i.e. the higher is the yield of activegalactomannans. This can be explained by the enlargement of the cellvolume due to the high degree of moistening. During the grinding theswollen cells are forced through a defined opening or crack, which cancause the cell membrane to tear, assuming that the swollen particles aresignificantly larger than the openings (the elasticity of the cells alsoplays an important role). When solutions in water are produced thegalactomannans are released from the cells which have thus beendestroyed, which is not the case with cells which have not beendestroyed. In these cases the galactomannans remain within the intactcells and do not contribute effectively to the viscosity of thesolution.

A moisture content of approximately 72% to 75% when grinding isacceptable for practical and technical reasons. Moisture levels lowerthan 72% when grinding lower the quality of the guarseed flour. A highercontent does not offer any advantages.

An advantage of the present invention consists in the possibility ofproducing products for solutions with viscosities for example as low as45 mPa·s, and those with up to 9000 to 10000 mPa·s at 1% concentrationin water at 25° C.

An additional advantage of the invention consists in producing pure guarproducts whose protein content is as low as 0.2 to 0.5.

The yield of pure guarseed flour varies between 70% and 80%.

Adding borax during the alkaline treatment or during a washing stepmakes the purifying process significantly easier. Excessive moisteningor swelling can be prevented by 0.05% borax, based on the weight of thesource split. The end product is unsuitable for use in foods afteraddition of borax, however, since traces of borax (approximately 20 ppm)remain in the end product.

Derivatization of the galactomannans in the guarseed flour is asignificant factor in the latter's solubility in cold water. Throughderivatization (e.g. carboxymethylation, hvdroxypropylation and thelike) one or more non-ionic, anionic or cationic groups are added,causing the galactomannans which are soluble in hot water to becomecold-water soluble. The derivatization usually takes place immediatelyfollowing the cleaning. As in the case of the addition of borax, asmentioned above, the use of derivatized guarseed flour is not allowed inthe food industry. Derivatized guarseed flour, especially guarseed flourwhich is derivatized by cation activation, does however find use in suchcosmetic products for instance as hair conditioner, body lotions andsimilar products.

The material resulting from the present invention is especiallyadvantageous, in that when dissolved in water it yields solutions ofgreat clarity. A 1% solution (0.9% dry substance) of the pure guarseedflour produced with this process shows a viscosity of 9000 to 10000mPa·s at 25° C., when such solutions are produced in a household mixerusing hot water at 90 to 100° C. The very high-viscosity products have aprotein and an A.I.R. content of only 0.2 to 0.6%. Through selection ofthe necessary processing steps (acid treatment, washing with water,treatment with IPA), an aqueous solution with a transparency of up to94% can be achieved. A 0.5% solution of the pure guarseed flour withextremely high viscosity at a wavelength of 500 nm with a 1 cm cuvetteat 25° C. shows a clarity of 74 to 81%, whereas untreated splitsolutions which have been produced at the same concentration andtemperature show a translucency of 46 to 48%. The comparable clarity ofsolutions of the precipitating fraction mentioned earlier, obtained byfractioning ground guar products in halogenated or fluorinatedhydrocarbon, is around 56%. The viscosity was determined in a BrookfieldRVT viscometer, the transparency of the solutions in aphotospectrometer.

The invention will be explained in the following section on the basis ofseveral examples. Splits of the highest quality were used as the sourcematerial for the described examples. Data such as the quantity of NaOHused for the neutralization, washing proportions, protein content andviscosity may be obtained from the corresponding tables.

EXAMPLE I

Treatment of the Splits With Concentrated Sulfuric Acid at RoomTemperature, Followed by a Neutralization and Washing Step

At the beginning of the cleaning it became clear that the concentratedsulfuric acid being used was not penetrating into the skin fragmentswhich were still connected to the endosperm halves. This was preventingthe underlying peripheral layers from being treated as desired.

In the course of this first series of trials (Trials 1 to 12, Table I)it was possible to reduce the protein content from 4% to 1.4%. Thisshows that most of the acid-treated layers were removed during thealkaline washing step to neutralize the acid.

The splits were weighed in a beaker and the necessary quantity ofsulfuric acid was quickly added. The mixture was stirred thoroughly witha plastic spatula.

During the acid treatment the splits were repeatedly mixed. Thenalkaline wash water was added and the slurry was stirred for 5 to 10minutes. The splits thus treated were recovered by filtration and, ifnecessary, washed again. The weight of the filtrates was recorded. Thecleaned splits were hydrated to a moisture level of 70% before grindingby adding the missing quantity of water.

The swollen splits were ground using a Retsch table mill.

EXAMPLE II

Treatment of the Splits With Concentrated Sulfuric Acid at 960 to 103°C. for 15 to 30 Minutes and Cleaning With Alkaline Washing Water, andAdditional Washing With Water

The splits were mixed with the necessary quantity of sulfuric acid (10to 15%), after being made slightly alkaline with a 0.5% NaOH solution(Table I, Trials 13 to 17). This allows monitoring of the aciddistribution. Alkaline splits are yellow, and turn amber-colored afterthe acid treatment.

The acidic splits were placed on a glass plate and put in a hot-air ovenat the requisite temperature (96° to 103° C.).

After this treatment the splits were washed, simultaneously neutralized,and washed again. The overall wash ratio was a maximum of 1:10. Theremainder of the treatment was the same as described in Example 1.

It was possible to lower the protein content of the purified guarseedflour to 1.2%. The viscosity data may be found in Table IV.

EXAMPLE IIA

The splits were treated as described in Example II. In addition to thewashing step with water the swollen, still alkaline splits in Trial 18(Table I) were dehydrated with hot isopropanol (IPA) at the ratio ofsplits:IPA of 1:2, and neutralized with acetic acid, which caused theprotein content to fall below 1%, a result which can be attributed tothe additional alkaline treatment of the proteins and their partialextraction.

In Trials 19 and 20 (Table I) the quantity of sulfuric acid was reducedto 8%; a dehydration step with IPA in the ratio splits:IPA of 1:1.8 wasincluded. The protein content of the purified guarseed flour wassomewhat higher than 1% (see Table I).

EXAMPLE III

Treatment of Splits With 8% Sulfuric Acid and Alkaline Treatment UsingVarious Quantities of NaOH at Elevated Temperatures, Washing With Waterand Dehydration

The conditions and the result of the trials described below are recordedin Table II.

The splits were weighed in a beaker and the requisite quantity ofsulfuric acid was added, after the splits were rendered slightlyalkaline with 5% NaOH.

The hydrolysis took place for 20 minutes at 105° C., after which alkaliwas added for only 7 minutes at 65° to 70° C. and the mixture wasstirred.

The alkaline splits were washed with water and dehydrated with IPA inthe proportions 1:1.6 at 550 to 62° C., then dried in order to removethe remaining IPA. The moisture content was brought to 70% and thesolits were ground.

In accordance with the process described before, 100 g of splits werefirst treated with 4 g of 5% NaOH. After 2 to 5 minutes the usualquantity of 8 g of 96% sulfuric acid was added and mixed as well aspossible.

The quantities of acidic mixture used for Trials 23, 24, 25 and 26 varyslightly from 8 g:

No. 23: 8.1 g

No. 24: 8.56 g

No. 25: 8.28 g

No. 30: 8.04 g

The hydrolysis of the peripheral layers took place for 20 minutes at102° to 106° C.

The acidic splits in Trials 24, 25 and 26 were washed with water (70°C.) in the proportions 1:2, 1:1.6 and 1:1.6, respectively, and thentreated with NaOH.

The other trials were treated once with 30% NaOH at elevatedtemperatures, then washed with water and dehydrated with IPA. Thealcohol was removed as thoroughly as possible with hot air. The splitswere moistened up to 70% and ground in a Retsch mill (see Table II).

In Trials 27 to 32 (Table II) the temperature of the wash water afterthe alkali treatment was 70° C. This increase in the water temperaturescarcely influenced the final viscosity (in a range of 4400 to 5750mPa·s), whereas washing at elevated temperatures after the acidtreatment caused a significant reduction in the viscosity (Trial no. 26:1550 mPa·s).

The protein content of the purified products varied in Trials 21 to 32between 0.67% and 1.11% (based on moisture content of 10%). In Trials24, 25 and 26 the acid-treated splits were first washed with water andthen treated with alkali, as described above. The protein contentdropped to 0.7% though there is risk of the galactomannans being brokendown (see Trial 26, Table II).

EXAMPLE IV

Treating the Splits With 6-11% Sulfuric Acid 96% at 105° C., Followed bya Neutralization and Washing Step and Alkali Treatment, Washing,Dehydration and Neutralization With Acetic Acid.

Table III summarizes the conditions of the trials described below. Theacid-treated, neutralized splits were deproteinized with a great excessof 30% NaOH or 23% NaOH at elevated temperatures of 45°-50° C. in Trials34 and 65 [sic!; apparently 35 is intended -Transl.], and 65°-70° C. inthe remaining trials.

The alkali-treated splits were washed twice with water, dehydrated andsimultaneously neutralized with 99% acetic acid in IPA. The ratio ofsplits to IPA was 1:1.6.

Most of the IPA still present was removed through treatment with hot air(70° C.), after which the splits were moistened up to 70% with water.After that the splits were ground in a Retsch mill.

The products, dissolved in water, exhibited viscosities and at the sametime extraordinary clarity and very low protein content. The results areshown in Table VI. The products from Trial 36, for example, had aslittle as 0.45% protein, but contained 1-2% sodium acetate.

EXAMPLE V

Removal of the Peripheral Layers of the Splits With 8% Sulfuric Acid96%, Followed by Neutralization or Washing and Hydrat on, an AlkaliTreatment, and Washing, Dehydration and Neutralization

In Trials 50 and 71-85, 100 g of splits were made neutral as usual. Thesplits of the other trials were first treated with the necessaryquantity of sulfuric acid.

In Trials 50 and 51 the neutralized splits were treated withstoichio-metric quantities of NaOH, using NaOH solutions atconcentrations of 30% and 23%, respectively. Then they were washed twicewith water, in both cases in proportions of 1:2. The subsequent alkalitreatment was carried out for 5 minutes at 65-70° C., after which thesplits were washed twice with water in the proportions 1:3.2 and 1:8.4,respectively, then dehydrated in IPA and neutralized with 99% aceticacid. The IPA was removed by exposure to hot air and the splits wereground as described in the preceding examples. The protein content was0.55% in Trial 50 and 0.65% in Trial 51.

Trials 52 and 53 were treated as described above, with the differencethat the first washing stage with water was performed only once in theproportions 1:2. The other conditions may be taken from the summarytable. It was possible to show that the alkali treatment at 65-70° C.allows more protein to be extracted than that performed at 50-55° C.

In Trial 53 H₃PO₄ was used instead of H₂SO₄. Less protein was removed,and lower viscosities were obtained.

EXAMPLE VI

Removal of the Peripheral Split Layers as in Example V, Omitting theWashing Step After the Acid Treatment.

After the hydrolysis of the peripheral layers the acidic splits wereneutralized with alkaline solutions of varying concentrations. Then analkali treatment was conducted for 7 minutes at 65-70° C. and theproducts were washed with water, dehydrated and neutralized, andprocessed as usual. The effect of the alkali concentration duringneutralization influences the final viscosity substantially, as shownbelow. The lower the NaOH concentration is, the greater the translucency(see Table IV).

In Trial 57 the neutralized splits were treated after the acid treatmentwith a small quantity of water before the treatment with soda lye wascarried out.

The earlier trials showed that moistening the neutralized, acid-treatedsplits has an influence on the viscosity. For that reason, the trialsdescribed below were carried out without this moistening. At the sametime the NaOH concentration was varied during the alkali treatment.

In Trials 68 to 73 (Table V) 19% NaOH was used, in Trials 74 to 76 24%,and in Trials 77 to 79 24.4%. In Trials 68 to 73 the alkali treatmentlasted 8 minutes, in Trials 74 to 79 10 minutes.

Trial 73 was washed at a higher ratio of split:H₂O. An additionalwashing step was performed at a ratio of 1:4. This additional cleaningdelivered a product of higher viscosity.

In Trials 71 to 79 (Table V) the source splits were made alkaline, whichexhibited a positive effect on the final viscosity levels.

Trials 78 and 79 show that alkaline dehydration with IPA, followed byneutralization in two steps, destroys the final viscosity.

In Trials 80 and 81 to 85 (Table VI) it was also possible to show thatthe alkali concentration or a washing step during or after theneutralization of the acidic splits causes a decline in the viscosity.

EXAMPLE VIA

For the Experimental Setup See Example VI, With the Difference That theFirst Neutralization is Followed by a Moistening Step

Trials 60 to 67 (Table V)

Trial 60 was conducted like Trial 57, and yielded a lower viscosity, buthigher transparency.

Trials 61 to 63, shown in Table VII, clearly show the positive influenceof the quantity of alkali used to remove the protein from the splits.

Trials 64 to 67 show that a longer period of neutralization after theacid hydrolysis of the peripheral layers allows production of guarproducts of higher viscosity (2790-3075 mPa·s as opposed to 2300 mPa·s)

The cleaned splits (based on 10% moisture) were dissolved indemineralized water at 90° to 100° C. in a 1% concentration, using ahousehold mixer.

EXAMPLE VII

Cleaning the Splits With Concentrated Acid, Alkali Treatment, Washing,and Dehydration and Neutralization

Trials 133 to 156

100 g of splits were incubated with 4 g of 5% NaOH for 10 minutes atroom temperature. 12 g of 95% H₂SO₄ were added and stirred for 7 minutesat room temperature. The reaction took place for 67 minutes at roomtemperature. 88 g of 23% NaOH were added to Trials 134 to 156 (Summarytable), 88 g of 18% NaOH to Trial 133. The mixture was stirred for 3minutes at 74° C. and the reaction took place for 14 minutes at 85° to62° C.

Trial 133 was stirred for 3 minutes at 57° C. and allowed to react for 7minutes at 74° to 64° C.

Two washes were performed, both in the proportions 1:8.3. The firstwashing phase lasted 15 minutes, the second 10 minutes.

The dehydration and neutralization with IPA took place in theproportions 1:1. Different quantities of acetic acid were used (seeoverall summary).

A dehydration step was performed with IPA in the ratios 1:0.6, and theremaining IPA was then removed by drying the splits in hot air.

The results are shown in the summary table.

EXAMPLE VIII

Neutralization of the H₂SO₄ Used, After Hydrolysis of the PeripheralLayers of the Splits, Employing Various Quantities of 50% NaOH(Under-neutralized, Neutralized and Over-neutralized), Followed by aWashing Step, an Alkali Treatment at Elevated Temperatures and ThreeSubsequent Washing Steps, Then Dehydration With IPA and Neutralization.

The cleaning conditions and the analytical data for Trials 159 to 161are gathered together in the summary table.

EXAMPLE IX

100 g of splits were incubated for 10 minutes with 4 g of 5% NaOH. Tothis were added 12 g of 96% H₂SO₄ and the mixture was stirred for 7minutes and allowed to react at room temperature for 10 minutes. Thealkali treatment was carried out with 20 g of NaOH as a 30% solution,based on the 100 g of splits. The treatment occurred for 7 minutes at53° C. Next a wash was performed with tap water for 5 minutes at a ratioof 1:4 and the splits were recovered by screening. Two washes with tapwater were performed for 7 minutes while stirring, and the splitsrecovered by screening. This was followed by dehydration andneutralization with IPA at a ratio of 1:1, and then recovery of thesplits by screening. This was followed by an additional dehydration ofthe splits with IPA at a ratio of 1:0.6. The remaining IPA was removedwith hot air.

In Trials 165 and 166 ethanol was used instead of IPA. Highconcentrations of sodium acetate were found.

Trials 167 and 168 were treated with KOH as an alkaline solution, inorder to investigate the solubility of potassium acetate in IPA. Nosignificant difference from sodium acetate could be found.

In Trials 169 and 170 additional variations of this process wereinvestigated. The slightly alkaline splits were incubated for 30 minutesat 100° C. in Trial 169 and at 80° C. in Trial 170, also for 30 minutes.Treatment with 12.4 g of 96% H₂SO₄ followed (see summary table).

EXAMPLE X

Over-neutralization of the Acid-treated Splits With 10% NaOH, AfterWhich They Were Treated With Hot 30% NaOH for 25 to 29 Minutes at 65° to69° C., Then Dehydrated and Neutralized.

Products with protein contents of approximately 0.5%, high viscositiesand high degrees of transparency can be produced in accordance withexample VIIIB.

EXAMPLE XI

Treatment of the Splits With Concentrated Sulfuric Acid at RoomTemperature, Neutralization With 10% Soda Lye, Alkali Treatment of theSplits With 23% Soda Lye, Washing of the Splits, Addition of 1.600 kgIPA, Grinding of the Splits, Neutralization With H₃PO₄, Grinding,Dehydration With 1.000 kg IPA, Drying.

To 1.000 kg of splits of the highest quality was added 0.120 kg of H₂SO4at room temperature over a period of 7 minutes; this was mixed and leftto stand at room temperature for 60 minutes. 1.000 kg of 10% NaOH wasadded to neutralize the sulfuric acid, while maintaining a temperatureof >53° C., and the mixture was mixed for 10 minutes at a temperature of53° to 63° C. 0.900 kg of 23% NaOH was added while a temperature of 78°C. was reached; this was mixed and left standing for 20 minutes at 70°to 75° C. with occasional stirring. Next three washings were performed,each for 7 minutes with 7.000 kg of tap water at room temperature. 1.600kg of IPA was added, and the splits thus treated were ground for 5minutes in a colloid mill. After neutralization with 85% H₃PO4 themixture was ground for 10 additional minutes and the deposit wasfiltered over 45 μm gauze. 1.000 IPA was added and stirred vigorouslyfor 7 minutes. The resulting guarseed flour was dried. The viscosity ofa 1% solution, measured in a Brookfield RVT viscometer at 25° C., was7900 mPa·s, the transparency of a 0.5% solution measured in a photometerwas 89.0%, the protein content was 0.43% and the A.I.R. content was0.71%.

EXAMPLE XII Partially Depolymerized Pure Guarseed Flour

Treatment of the Splits With H₂SO₄ at 105° C., Neutralization With 30%Soda Lye, Washing, Alkali Treatment With 30% Soda Lye, Washing,Dehydration and Neutralization.

1.000 kg of splits was treated with 0.060 kg of 96% H₂SO₄ for 18 minutesat 105° C. 0.157 kg of 30% NaOH was added for neutralization and themixture was incubated for 2 minutes at room temperature. Next the splitswere washed for 2 minutes at room temperature with 2.000 kg of tapwater. To partially deproteinize the splits, 1.060 kg of 30% NaOH wasadded, the mixture was stirred for 4 minutes, and then allowed to reactfor 7 additional minutes at 65-70° C. The splits were then washed with2.4 kg of tap water for 6 minutes at room temperature, after which onceagain 10 kg of tap water were added and the mixture was incubated for 5minutes at room temperature in order to moisten the splits. 1.6 kg of99% water-free IPA was added, incubated for 15 minutes at 55-62° C., andthen treated with 0.066 kg of 99% acetic acid. The splits were groundwith a hammer mill.

The viscosity, measured as described earlier, was 60 mPa·s for a 1%solution, the translucency was 94% and the protein content was 0.65%.

EXAMPLE XIII

Partially Depolymerized Pure Guarseed Flour With Extremely Low ProteinContent and Aqueous Solutions of Excellent Clarity

The splits (1 kg) are treated for 60 minutes with 8% by weight of 96%H₂SO₄ at room temperature and then treated first with 670 g of 10% sodalye followed by 1.060 kg of 30% soda lye. In Trial C (see table) thesplits were treated for 20 minutes with 50% soda lye at 67° C. Thesplits were washed for two 2-minute period with tap water in theproportions 1:5 and one time for 6 minutes with tap water in theproportions 1:8. The splits were dehydrated with 1.4 kg of 99%isopropanol and the cleaned splits were then ground in a colloid mill.

The suspension was left standing for sedimentation to occur, and after15 minutes 4.0 to 4.6 liters of the top liquid were decanted, afterwhich 1.1 kg of 99% IPA was again added. The suspension was heated to60° to 65° C. in a reflux vessel and this temperature was held constantfor 2 hours.

A further addition of 1.2 kg of 99% IPA makes dehydration easier. Thealkaline products were neutralized with 36 to 60 g of 99% acetic acidand brought to the desired fineness by being wet ground again in acolloid mill. The products were recovered by filtration and subsequentdrying of the “wet” filtrate at 70° C. In Trial C 10 ml of 30% H₂O₂ wasadded to accelerate the depolymerization during the alkaline treatmentin the water/IPA suspension.

The following results were obtained:

Product A B C Yield in g 792 735 725 Water content % 9.6 11.2 6.8 1%viscosity mPa 5.20 UpM Measured temp. 25° C. Solution 1 1250 850 35Solution 2 1650 900 35 0.5% transmission 1 cm cuvette/500 nm Solution1/water 1:1 85.1 87.0 92.0 Solution 2/water 1:1 96.0 95.8 97.2 Protein %Nx 6.28 0.25 0.23 0.31

Solution 1 was produced at 25° C. and solution 2 at 90° C. in a mixerand then cooled to 25° C.

EXAMPLE XIV

10 kg of splits were treated at 35 to 40° C. with 1 kg of 96-98% H₂SO₄for 1 hour, and the precipitated material was stirred at intermittentintervals for 30 seconds at a time. The treated splits were thenneutralized with 1.64 kg of 50% NaOH, which causes a rise in temperatureto 50° to 70° C. After 15 minutes the neutralized splits were washedtwice for 2 to 3 minutes with tap water in the proportion of splits totap water of 1:5, and then once again for 6 minutes in proportion ofsplits to tap water of 1:8. The wash water was suctioned off in eachcase. The cleaned splits take on 80 to 82% water during the washingprocess. The strongly hydrated splits were ground in a hammer mill witha capacity of 30 kg/h during suctioning of hot air at approximately 110°C., so that the product could be dried in the same working step.

The products produced in this manner exhibit viscosity values between5000 and 8350 mPa·s in aqueous solution at a concentration of 1% basedon a water content of 10% of the ground product. The solutions wereproduced as described earlier, in a household mixer with hot water at90° C.

The clarity of the aqueous solutions, thinned at 1:1, measured at alayer thickness of 1 cm, was 1-67.5%.

The products produced in this manner can be converted to nearlywater-clear products when dissolved in water, in a second process with8-10% NaOH (based on the starting weight of the splits) in aqueous IPA(35 percent by weight) at 65° to 70° C. and subsequent washing withaqueous IPA.

The purified alkaline product was neutralized with acetic acid;depending upon the conditions during washing these products can containup to 12% sodium acetate.

EXAMPLE XV

In the following section various processes are described, by analogywith the earlier examples, which furnish pure guarseed flour fortechnical applications.

A. Splits washed with water and treated with acid are subjected to asubsequent alkali treatment at various temperatures and reaction times,depending upon the specificity of the final product. After the alkalitreatment the splits are washed with water in order to remove thedecomposition products of the alkali treatment as well as dissolvedproteins and alkali.

Washing without borax leads to water levels of up to 85% of the treatedsplits. These severely swollen splits are dehydrated with aqueous IPA,and after partial dehydration are neutralized (about 5 minutes afteraddition of the aqueous IPA).

The partially dehydrated splits can be wet ground in a colloid mill,recovered by filtration, and further processed.

B. The splits are treated as described in A, but the alkali treatment,either of the splits or as a coarsely ground wet product, takes place ina filtration and washing unit for 1 hour at 70° C. This treatment isfollowed by extraction with aqueous IPA, neutralization and dehydration,likewise by means of aqueous IPA. The moist cake obtained after thistreatment can be dried and further processed into the appropriate endproduct according to the requirements.

C. The treatment of the splits is the same as described in B., but theaddition of H₂0₂ yields a pure guarseed flour of low viscosity. Thisleads to an improvement in the clarity of the solution of the endproducts.

D. The treatment of the splits is the same as described in A., but usingreagents such as sodium monochloracetate or glycidyl trimethyl ammoniumchloride to produce anionic or cationic products of great clarity. Thesereagents are placed in a reaction vessel after the product has runthrough the filtration and washing unit (see B).

The moist cake of pure guar gum is dried in a rotary drier with hot airat 80° C. The dried products are pulverized to the desired size and thenpackaged.

Additional examples to illustrate the invention may be found in theaccompanying tables, starting on page 11.

What is claimed is:
 1. A process for producing a non-derivatizedpolygalactomannan guarseed flour, having a viscosity of 45 to 10,000mPa·s as a 1% aqueous solution, a content of proteins and acidnon-hydrolyzable substances of 0.8 to 0.9%, and a transparency of atleast 70% when measured as a 0.5% aqueous solution at a wavelength of500 nm, said process consisting essentially of the steps of: (a)treating guar splits with an acid; (b) washing said acid-treated splitsone or more times with water and/or neutralizing said acid-treatedsplits with a first aqueous alkaline solution; (c) treating said splitswith a second aqueous alkaline solution; (d) washing said splits withwater; and (e) dehydrating said splits with an aqueous alcohol solution.2. The process according to claim 1, wherein said acid used in step (a)is concentrated sulfuric acid in a concentration ranging from 70% to 96%of an aqueous solution and in an amount ranging 5% to 20% by weight ofsaid splits.
 3. The process according to claim 2, wherein said sulfuricacid is in a concentration of 96% of an aqueous solution and in anamount ranging 8% to 12% by weight of said splits.
 4. The processaccording to claim 1, wherein said sulfuric acid used in step (a) is ina concentration lower than 70% of an aqueous solution.
 5. The processaccording to claim 1, wherein said first aqueous alkaline solution is anaqueous soda lye solution.
 6. The process according to claim 1, whereinsaid first alkaline solution used to treat the neutralized split is sodalye at a concentration ranging 20% to 40% by weight of said splits. 7.The process according to claim 1, wherein said second aqueous alcoholsolution is selected from the group consisting of: methanol; ethanol;and isopropyl alcohol.
 8. The process according to claim 1, furthercomprising the step of neutralizing said splits with a solution of anorganic acid.
 9. The process according to claim 1, further comprisingthe step of moistening said splits which were dehydrated with an aqueousalcohol solution, to achieve a moisture level ranging 60% to 80%. 10.The process according to claim 1, wherein said splits have a proteincontent of 4.2% by weight and have a level of acid non-hydrolyzablesubstances at 1.8% by weight.
 11. The process according to claim 1,wherein the guarseed flour yield of from about 70 to 80%.
 12. Theprocess according to claim 1, wherein the guarseed flour has atransparency of 94% as a 0.5% solution at a wavelength of 500 nm.